Installing on macOS 10.12 (and earlier) appears to be unsupported with lmms-1.2.0-rc8-mac10.13.dmg. Some people are unable to upgrade to macOS 10.13 without breaking other programs, while some are stuck at macOS 10.11 due to hardware limitations. e.g. Mac Pro and others from 2008/2009.

Is there a plan to support macOS 10.8 to 10.12 in the 1.2.0 final release?

EDIT: Never mind, they must have uploaded lmms-1.2.0-rc8-mac10.8.dmg in the last 15-20 hours, because I didn't see it earlier.